It's a pain to do but it won't cost you any money. None of the cameras you have include Timecode (not 'Time/Date) which is the numerical time count on tape or digital recording media (Hours:Minutes:Seconds:Frames = 00:00:00;00) Hours 00-99, Minutes 00-59, Seconds 00-59 and Frames 00-29. Since your cameras don't have actual timecode and your cameras don't have running counts either here's what you can do:
1. Make one camera your 'Main'. This will be the camera that you'll point towards the stage. If you don't have anyone else working with you who knows what they're doing, then you'll put this camera on a tripod where you'll have an unobstructed view of the stage. You'll need to put some sandbags (soft leg or wrist weights work just as good) on the tripod to hold it down. Set the image frame where all you see is the stage and the band where it looks good (look at some concert videos to see what I mean) and 'lock down the tripod' so it won't move. Make sure your battery is fully charged because once you start it don't touch it until the band's set is over (including any encores.) This will be your video and audio reference footage. Make sure you bring a friend who will stay with the camera and make sure no one bumps it (including themselves), knocks it over or walks off with it. Without this footage you will have hell trying to match up your other cameras and sound during the edit. So don't mess this up!
2. Take another camera to use as your 'cut camera'. This will be your 'roving camera' as it will move around getting different angles during the show. Use this one to get close ups of the band, their hands playing instruments and shots of the audience during the show. Save yourself from pulling your hair out when it comes to editing by following these steps;
Cut shots last 10 seconds with a 3-5 second 'head and tail'. That means when you get your shot set up (in focus, properly exposed, etc) count of 3-5 seconds while you hold the camera steady and then count off 10 seconds while shooting whatever you're pointing at. After ten seconds, count off 3-5 more seconds then move onto the next shot. Having those 3-5 second heads and tails on your clips will make it easier to edit your cut shots with the footage your main camera gets. Unless there's something incredibly interesting happening,10 seconds per cut shot is all you need. You'll be surprised at how long 10 seconds is when trying to edit! Don't stand in one place for the whole show while trying to get cutshots. Your main camera is already doing that. Don't be afraid to move around and get close! If you want your video to be boring, just stand in one place….
3. Use your GoPro as a 'Stage' or 'Flying' camera. If you've got mounts for it, set your GoPro right up on the stage (but out of the way of the performers) so you can get some eXtreme close-ups! If you've got somebody else working with you, mount the 'Go' on a boompole and use it as a 'flying camera' you hold over the audience or near the stage. Make sure the boom is stable and not too long so it isn't heavy or hits the ceiling, etc. The Go is a wide-angle camera and small enough you can get some crazy good shots with it. For god's sake don't use it hand-held! You won't be able to keep it steady and it will shake like mad. You'll be lucky to get any useable shots at all.
4. If you can, see if the guy running the mixer will let you patch into the mixer to get your sound directly. It will be a whole lot cleaner than anything you'd get with your cameras even if you have good mic's. Your Canon's have an audio input (3/4" 'mini' mic input) so if you can put your main camera close to the mixing board, you'll need an XLR-Mini adapter so you can plug into the board and either a long Mini input cable to plug into the adapter and then into your camera. You'll need to tape the cable to the tripod (please don't use duct or electrical tape) so it won't get yanked out by accident. If you can use a wireless mic setup that would work much better long as there's no interference. If you can get your hands on a small digital recorder like a Zoom H1, then you can just use the same setup to connect the recorder to the mixing board and get clean sound that way.
Okay, now there's no 'special software' that's going to make all this stuff magically line up. That's why I laid out all those steps for what you should do. If you're using a Mac you can probably do this stuff in iMovie or Quicktime. If you're using a PC Sony Music Studio or Adobe Premeire Elements are good and inexpensive choices among many.
Whatever you get, you'll need at least two video tracks, one for your main video footage which you will layout as your refernence track and the other to lay in your titles, cutshots and GoPro shots. You'll also need at least two audio tracks. One for the main audio you got from either your main camera or your digital recorder. Whichever has the cleanest audio, use that one. The other track is for any audio voiceovers like if you're going to say something about the show at the beginning or end like an offscreen host.
Lay down the main camera video and if you had a recorder, your main audio. Sync those up first. Once you have those synced then it things get easier. Go through your cutshots and Go shots and start piecing them over your main video footage to make the show look more dynamic. Use the audio from the cutshots with the video at first to make sure anyone talking while the music is playing or the frontman/woman/announcer is speaking matches up with your main audio.
5. Most important, BEFORE you go to shoot the show, go to the venue and scout the place out. See where everything is going to be, where you can setup, how much room you'll have and where you can and can't go during the show. Tell the people running the show you're coming to shoot at the request of the band. Make sure your friend in the band lets them know you're coming. You may be able to get a free pass! Talk to the sound engineer and ASK if you can patch your camera/recorder into the mixing board. Bring your own adapter, cables and or wireless setup and test your gear BEFORE the show starts. Better if you can do this before the day of the show or early in the day as possible. The engineer's not going to have time or desire to fool with your the closer to showtime it gets.
So, do these things and the odds are excellent you will have good footage to make your video with. Oh yeah, one more thing turn off your Autofocus and use the Manual Focus setting for both your canons. If it's the standard concert, it will be dark except for stage lighting and your Autofocus will make your life a living hell as it constantly goes in and out of focus. Good luck!